HubDoctor Pro Bearing Upgrade for Mavic Freehub - Any Experiences?
buckmulligan
Posts: 1,031
At the weekend I decided to break open the toolbox and tackle an issue with my Mavic Ksyrium Elites that had been annoying me for a while. As a bit of background, I was experiencing a lot of cassette wobble from a worn nylon bushing in the freehub that was starting to cause the chain to skip occasionally under load as though the indexing was a little out; I'd serviced the whole drivetrain a few weeks ago trying to sort it out but to no avail, so bit the bullet and ordered the HubDoctor Pro Bearing Upgrade Kit on eBay from the US.
The kit basically replaces the white nylon bushing in the freehub with an aluminium adapter that houses a cartridge bearing, supposedly running with a lot less drag and requiring a lot less servicing:
The aluminium adapter and cartridge bearing in the rear of the freehub needs some space back there, so the system ditches the rubber seal that usually sits behind the freehub and has a new one that seats around the edge of the aluminium adapter and seals against the edge of the hub body. The only problem with this is that this new seal design seems to create a hell of a lot of drag when freewheeling. When I install everything back on the bike without the seal in place, it's absolutely fantastic; I can spin the rear wheel up and several minutes later it's still coasting along quite happily! However when I put it all together with the seal in place, there's a ton of drag when freewheeling, the rear wheel tries to drive the pedals around and if you hold them still the rear derailleur cage lurches forward and there's a ton of chain sag. It was just about rideable when I reassembled it all but after leaving the bike standing for a few hours the freehub drag got a hell of a lot worse and was basically unrideable with the seal in place. I'm 99% sure it's all assembled correctly, because it's absolutely fine without the seal in place, but obviously I'm not so keen on running it like this for any prolonged period of time. Is it possible that the lube that I've used inside the freehub and on this seal has caused the rubber to swell and exacerbate this drag?
Any help or experiences with this kit are much appreciated!
TL;DR - has anyone used this system? If so, does it run completely drag free and what lube are you using in the freehub body and for the rubber seal?
The kit basically replaces the white nylon bushing in the freehub with an aluminium adapter that houses a cartridge bearing, supposedly running with a lot less drag and requiring a lot less servicing:
The aluminium adapter and cartridge bearing in the rear of the freehub needs some space back there, so the system ditches the rubber seal that usually sits behind the freehub and has a new one that seats around the edge of the aluminium adapter and seals against the edge of the hub body. The only problem with this is that this new seal design seems to create a hell of a lot of drag when freewheeling. When I install everything back on the bike without the seal in place, it's absolutely fantastic; I can spin the rear wheel up and several minutes later it's still coasting along quite happily! However when I put it all together with the seal in place, there's a ton of drag when freewheeling, the rear wheel tries to drive the pedals around and if you hold them still the rear derailleur cage lurches forward and there's a ton of chain sag. It was just about rideable when I reassembled it all but after leaving the bike standing for a few hours the freehub drag got a hell of a lot worse and was basically unrideable with the seal in place. I'm 99% sure it's all assembled correctly, because it's absolutely fine without the seal in place, but obviously I'm not so keen on running it like this for any prolonged period of time. Is it possible that the lube that I've used inside the freehub and on this seal has caused the rubber to swell and exacerbate this drag?
Any help or experiences with this kit are much appreciated!
TL;DR - has anyone used this system? If so, does it run completely drag free and what lube are you using in the freehub body and for the rubber seal?
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http://pedros.com/faqs/which-lubricant- ... c-freehub/ Whatever you use needs to be low viscosity.
Yeah, I thought so too. It's expensive but hopefully the magical combo of better performance and less maintenance. It's certainly cured the play I had in the freehub, so that's one issue solved but replaced by another at the moment!
Thanks, that's useful info. Shimano Mineral Oil was going to be my next port of call, but thought I'd canvass some opinion first! I've used it in the freehub before but thought it was slightly too light to keep that nylon bushing well lubed so went for something slightly thicker. Now that's no longer an issue I'm thinking of giving it another shot. How has your's held up since installing it?
Glad to hear it!
As a quick update, I contacted the vendor enquiring about recommended lubes and he said that he'd ship out some extra seals and see if it cures the issue. Great service considering he's across the atlantic.
Fingers crossed!
My experience has been reasonably good. It took tow goes to get it right.
The first attempt when smoothly and following the instructions was dead easy.
https://photos.app.goo.gl/3H8fzwvWpqauPnPf7
I thought I had sanded the hub enough when I could squeeze the freehub back on however after assembly there was still a lot of drag. I tried to go for a ride but because there was so much drag there was a lot of slack chain and it looked to me that freewheeling with a lean to the left could have resulted in the spokes and chain clashing.
Searching the web suggested that running in the repair would reduce the drag and that the drag was related to the seal installed on the inside face of the freehub. However the only way to run it in was to ride it and let it freewheel!
I messaged Doctor Hub asking for his thoughts. He suggested a 2nd washer or that I had not sanded the hub enough.
I dismantled the hub again and spent a few more minutes sanding the hub until the freehub slipped on more easily. I then rebuilt and tested it on an upside down bike. It freewheels quite nicely although there is a rough spot. I've put it onto the turbo and will give it a run (although not a lot of freewheeling) this week.
Tips:
If you can get the right sealed bearings I am not sure you need the Hub Doctor kit. At £50+ from the USA it's expensive for 2 bearings, some sandpaper and a basic tool which helps keep the sanding consistent around the hub.
If you do buy the kit you will need more sandpaper or, even better, emery cloth.
The Hub Doctor tool is useful but doesn't seem to be be critical. Patience and care will get the same result.
Don't drop the spring out of the pawls. They are small and finding one in a busy, poorly lit garage is a nightmare.
Mine were 7 years old so well beyond warranty. I think the design remains the same.
I use a light gun oil, just because i had some and it works brilliantly. Because it doesn't say bike on the tin its not expensive either.
It's hard to tell from all of those drawings, but doesn't your kit use the aluminium bearing adaptor that presses into the back of the freehub? This is the critical, custom-machined part that costs the money, not the bearings.
First time I used the hubdoctor set was in 2012 and again in 2017. Both still going strong. A worthy upgrade.
To cap it all Mavic are apparently redesigning their hubs, bit late for most of us though!